1. The Field of the Invention
This invention relates to transporting and distributing particulate material and, more particularly, to novel systems and methods for drop and broadcast spreading of materials used in turf care.
2. The Background Art
Agrarians have always been interested in efficiently managing their land. Common land management tasks include spreading substances such as seed, water, fertilizer, and the like. The quality of the land and its produce often depend on the even distribution of these vital substances. Uneven distributions result in waste and may even hinder or halt the progress of the desired vegetation. For these reasons, agrarians have developed various spreaders to rapidly and evenly distribute seed, fertilizer, water, sand, other soil amendments, and the like, thus, providing improved or ideal conditions for the vegetation of their choice.
In modern times, spreaders have been applied to the treatment of lawns and turf, particularly for parks, athletic fields, golf courses, and the like. Modern spreaders are also used for other purposes such as distributing cinders, salt, sand or other de-icing materials on winter roads. Broadcast spreaders and drop spreaders are the most common varieties of spreaders. A broadcast spreader typically includes one or more rotating spinners. The rotation of the spinner generates a centrifugal acceleration in the material deposited thereon, resulting in an arcuate distribution upon tangential release. In larger capacity models, broadcast spreaders often rely on a conveyor to deliver material to the spinners. Broadcast spreaders are suited for applications involving smaller amounts of material spread over large areas. For example, broadcast spreaders are often helpful in spreading fertilizer, pesticide, seed, top-dressing material, and the like.
Drop spreaders typically distribute a material by simply dropping it through one or more apertures directly onto a ground surface. On larger capacity models, a conveyor may assist in the removal of the material from a hopper. A conveyor may also assist in the metering out of the material. Drop spreaders are well suited for spreading larger amounts of material over a limited width. Typically, drop spreaders only distribute the material across a width roughly equivalent to the width of the spreader itself. Drop spreaders are often used as top dressers to apply a layer of sand, topsoil, gravel, or the like.
Recent advances in turf care, particularly golf green care, suggest that lighter more frequent applications of selected materials maximize turf quality. Broadcast spreaders are particularly well suited for such light applications if they can provide uniformity. However, there are still many applications that require a heavier, more controlled application of material. Heavy applications often require a drop spreader. As a result, combination drop and broadcast spreaders have been introduced.
While an improvement, combination spreaders are still susceptible to many of the weaknesses associated with the individual drop and broadcast spreading machines. Additionally, combination spreaders encounter difficulty in handling the wide variety of materials that are distributed by both drop and broadcast spreading devices.
Top-dressing materials used on sports turf and golf fairways and greens typically have some combination of sand, silt, clay, peat, lime, gypsum, and/or soil. When the moisture content is high, top-dressing material becomes cohesive and resistant to flow. As a result, it becomes more difficult to remove the material from the hopper and provide a consistent metering. Consequently, conveyors having chevron, herringbone, or other raised patterns on the surface have been introduce to assist in drawing the top-dressing material from the hopper though a metering port.
Conveyors with raised patterns cause two problems. First, the wet mixture clings to the conveyor between the raised portions of the surface pattern. Instead of falling off the conveyor as desired, the top-dressing material often sticks to the carrier. When top-dressing material does fall off the conveyor, it often does so in uneven clumps. Removal of the top-dressing material from conveyors with raised patterns has proven to be a difficult challenge. A simple scraper does not work well with raised patterns. Other more effective removal devices are complicated and inhibit the addition of other distributing attachments.
A second problem occurs when all of the recesses between the raised patterns become filled with top-dressing material. In effect, a conveyor with recesses filled acts just like a smooth conveyor. As a result, the device again is faced with the challenge of drawing the moist top-dressing material from the hopper with consistent metering.
Other challenges of combination spreaders must be addressed regardless of the moisture content of the material to be distributed. For example, maintaining a desired distribution pattern of equal density is another common challenge. Much effort has been invested in producing an even lateral (i.e. side to side with respect to the direction of travel) distribution. For example, if a broadcast type spreader is used to apply top-dressing material to a golf green, any uneven distribution will soon be noticeable. Moreover, as uneven applications accumulate, the problem is exacerbated and the result must be corrected with considerable difficulty.
Another challenge in combination spreader design relates to loading heights. For ease of loading, it is advantageous to minimize the loading height. However, low profile spreaders have difficulty maintaining a sufficient trailing clearance. The trailing clearance is the spacing from the tires to the lowest part of the spreader behind the tires. A sufficient trailing clearance is necessary to avoid damaging turf, or the spreader itself, as the spreader is moved on and off of elevated greens and through undulations.
Trailing clearance and other operational constraints are often at odds or balanced with one another with difficulty. For example, converting a drop spreader to a broadcast spreader often entails the addition of a funnel. Typically, twin spinners are employed on a broadcast spreader. Often the spinners are placed adjacent one another. Funnel height restriction, imposed by overall height and trailing clearance considerations, often results in funnel angles so shallow that the wet, cohesive material sticks to the funnel walls stopping further flow.
Additionally, with typical spreaders, due to the larger number of variables, it is difficult to know how much material is actually being distributed at any given time. For example, a user may be faced with adjusting spinner speed, spinner angle with respect to the ground, metering-port dimensions, conveyor speed, and spreader speed to achieve a desired application. The characteristics of the material to be distributed must also be considered. These variables are too numerous for a user to take into consideration when trying to generate a desired application of material.
Safety considerations also present challenges to spreader design. Powered broadcast spreaders, for example, use rotating paddles to throw material in a wide pattern. Rotating paddles cannot be completely covered or protected without adversely affecting the function of the broadcast spreader. Rotating paddles are typically shielded on a portion of their periphery to control the spread pattern and direct the stream of the distributed material. If a user were to inadvertently put a foreign object such as a hand or foot in the path of a rotating paddle, the paddle would shear the foreign object as it passes by the edge of the shielding. On typical powered broadcast spreaders the shear point, where the paddle passes the edge of the shielding, is exposed and readily accessible to the user.
Various solutions have been proposed to lessen the danger of the exposed shear point. However, these proposed solutions do not remove the shear point. Rather, they act to merely impede access to the shear point. With such measures, if a hand or finger did inadvertently enter the path of the spinner at the shear point, significant damage would still occur. Meanwhile, obstructions to hands are often obstructions to distribution of the granular material.
The foregoing challenges and design considerations, as well as others, are addressed by the present invention.